The power and fuel efficiency of a gas turbine engine is a function of the temperature of the combustion gases at the inlet to the turbine. The temperature is generally maximized consistent with turbine and nozzle structural integrity. The maximum turbine rotor inlet temperature allowed by current state-of-the-art uncooled metal turbine rotors is approximately 2000.degree. F. Increasing the turbine rotor inlet temperature beyond 2000.degree. F. requires the use of advanced super alloy blade materials which are generally not compatible with the mechanical properties of the rotor hub.
A solution to this incompatibility problem is to adopt a dual-property approach to the fabrication of the turbine rotor. In large gas turbines, where size and complexity constraints are not acute, this is accomplished by using discrete blades of a high rupture strength material mechanically attached to a high burst strength disk. However, the physical size, cost, and complexity associated with this dual-property rotor concept has heretofore precluded its use in small, lightweight gas turbine engines.